If you were looking to buy a house right now, you'd be looking at a bunch of options that are worse than what you currently have. You experience this as lock-in but in reality the "problem" is just that you have something significantly better than anything you (or others) can find on the market right now. And of course that's actually a fantastic boon.
But part of that is because people who would otherwise want to sell their house are choosing NOT to, because they don't want to lose their great mortgage. If we didn't have these long, fixed rate, mortgages, there would be a lot more housing liquidity and prices wouldn't be so inflated.
Now, there is a cycle of "rates go down, there is a flurry of re-finances and everyone locks in the lower rates and new buyers enter the market, and housing prices go up and up", and then rates go up, but housing prices don't go down because people can't afford to buy the houses at the same prices anymore, and so no one wants to sell (because the current owners are paying below market rates for their mortgage, so they face no selling pressure like they would if there WEREN'T long term fixed rate mortages), so there is no decrease in prices.